The regional feasibility of augmented local water storages

Local water storages can contribute significantly to meet regional demands for water and offer governments a strategy for reducing or delaying investment in large-centralised water infrastructure. Local water storages include ponds, canals, drainage systems and subsurface aquifers. Augmentation of local water storages and determination of their regional feasibility is not fully understood. Cost-effectiveness, physical characteristics, interactions between measures and interactions with the national water system are of crucial importance here. Dutch national and regional water managers currently negotiate about water distribution and regional self-reliance. However, in the Dutch negotiation, the potential of local groundwater storage, as a way to overcome periods of drought, is generally underestimated.

In this study, we assessed the potential of local groundwater storage measures, regarding technical storage capacity (in cubic meters (m³)) and costs (euro/ha/year and euro/m³), in a case study area in the Netherlands (Wieringen + Wieringermeerpolder) by means of a novel dynamic modelling method, called the Fresh Water Options Optimizer (FWOO).

The first results of the FWOO method show that Wieringen + Wieringermeerpolder is able to store between 35 million cubic meters (Mm³) and 80 Mm³ with the seven local groundwater storage measures that are taken into account. This is 80% to 180% of the summer demand, based on a water demand of 200 mm during the growing season. The costs for the combination of measures in Wieringen + Wieringermeerpolder are between 0.10 euro/m³ and 0.13 euro/m³.

The FWOO is not ready yet. Not all dynamics of augmenting local waters storage measures are (modelling wise) properly addressed. For example, temporal aspects of water supply and demand are not yet taken into account. Besides, preferences and needs of other water users (nature, industry, and urban areas) might lead to undiscovered options to store and reuse water. To inform regional water managers, efforts to compare the costs of local measures with centralized water storage and provision strategies are needed.

Although the model is still under improvement, these first results open new perspectives on the potential of regional self-reliance and should be taken into account during negotiations around water distribution between national and regional water managers.